Referring to FIG. 1, an electrochemical biosensor 8 is adapted for measuring concentration of an analyte in a sample liquid, such as blood sugar concentration in a blood sample, or the concentration of heavy meal pollutants in a wastewater sample. As shown in FIG. 1, the electrochemical biosensor 8 includes an insulating substrate 81, a metallic conductive layer 82 formed on the insulating substrate 81 by printing, an insulating layer 83 disposed to partially expose the metallic conductive layer 82, a reagent-reactive layer 84 in electrical contact with the metallic conductive layer 82, and a cover plate 85. Although the electrochemical biosensor 8 may achieve the primary goal of measuring the analyte concentration in the sample liquid, the metallic conductive layer 82, which is formed by screen printing, may exhibit relatively high electrode impedance which results in attenuation and interference of electrical output signals. In addition, the metallic conductive layer 82 of the electrochemical biosensor 8 may consume a relatively large amount of metallic raw material which increases the production cost.
Referring to FIG. 2, another electrochemical biosensor 9 is shown to include an insulating substrate 91, a pair of electrodes 92, an electrochemical reactive layer 93 and a cover plate 94. The insulating substrate 9 is formed with a reaction chamber 911 and a pair of through holes 912 in spatial communication with the reaction chamber 911. The electrodes 92 are respectively disposed in the through holes 912, and the electrochemical reactive layer 93 is disposed in the reaction chamber 911 to be electrically coupled with the electrodes 92. The cover plate 94 is disposed to cover the reaction chamber 911. Although the electrochemical biosensor 9 may also achieve the primary function of measuring the analyte concentration in the sample liquid, the electrodes 92 and the substrate 91 are separately made, and a relatively complicated assembling procedure is therefore required. In addition, such configuration of the electrochemical biosensor 9 requires relatively low tolerance in making the electrodes 92 and the through holes 911 and thereby increases the production cost.